An electronic device of this kind, designed as an output stage for driving a brushless electromotor, is known in the field. As semiconductor chips, the device has a plurality of transistors which are mounted on a printed-circuit board. On their front and back flat sides, the semiconductor chips have electrical points of contact, of which one is surface-bonded in each case on the rear side of the semiconductor chip facing the printed-circuit board, to a conductor part. A bonding wire is connected in each case via an ultrasonically welded connection to the points of contact located on the front sides of the semiconductor chips. The bonding wires are made of aluminum, and their diameter is limited to approximately 0.3 to 0.5 millimeters. Thus, they have a relatively high ohmic resistance, which can amount to over 1 mΩ. This is particularly disadvantageous when driving electromotors which have only a small number of windings. Electromotors of this kind can, in fact, be manufactured inexpensively, however they require a relatively high motor current, from which the requirement arises of designing the motor circuit and, thus, also the output stage to be as low-resistance as possible.
From the field, one also already knows of an electronic device in which the semiconductor chip is electroconductively surface-bonded on one contact side via a soldering-agent layer to a metallic conductor part. The semiconductor chip and the conductor part have different thermal expansion coefficients. Since the semiconductor chip and the conductor part warm up when the device is brought into circuit, due to the dissipation heat generated primarily in the semiconductor chip, they expand to different degrees. To reduce the mechanical stresses resulting from this variable expansion in the semiconductor chip, the softening temperature of the soldering-agent layer is adjusted to the operating temperature of the device in such a way that the soldering-agent layer is doughy or liquid at the operating temperature. To prevent the soldering-agent layer from flowing off from the side of the soldering gap formed between the conductor part and the semiconductor chip, the soldering-agent layer is laterally bounded by a flow-off protection device. However, the disadvantage of the soldering-agent layer is that it still has a relatively high electrical resistance and a correspondingly low thermal conductivity.